As computers have become smaller and more powerful, there have been recent efforts to provide portable, hand-held computers for rendering electronic content in a manner that is similar or identical to the way content is presented in a printed paper book or other document. Thus, much effort has focused on providing a user interface for computers that fosters an immersive reading experience, or the sensation of being “lost” in the electronic document.
One primary advantage that computers offer over printed paper documents as a means for presenting documents to users is that computers can make added functionality available to the user. Such functionality may include navigational functions that permit the user to navigate to and thus view other pages of the document, or view other documents, instantly and without considerable interruption in the user's reading experience. Such functionality may also include interaction with content, such as highlighting, annotating or looking up word definitions or synonyms in dictionaries or thesauruses.
Yet providing a user access to the enhanced functionality available in computer-implemented books without detriment to the immersive reading experience presents a challenge. For example, the prior art provides traditional user interface features, such as pull-down or pop-up menus or help balloons through which users may access additional functionality while viewing an electronic document. However, such traditional user interface features clutter the viewing area and detract from the user's immersive reading experience. Accordingly, it would be advantageous to provide a user interface which offers a user access to the enhanced functionality that can be provided by a computer-implemented book or document, yet which maximizes the potential for the user to have an immersive reading experience.